Cyclic stratigraphy has been recognized in the Newark Basin for many years. Each package, referred to as a Van Houten Cycle (VHC), generally has three divisions: shallow lake, deep lake, and subaerial exposure. Van Houten (1964) first proposed that Milankovitch orbital forcing was responsible for the manifestation of these ~21 kyr cycles. Although root traces have been observed in VHCs by others, no detailed paleopedological analysis has been performed that examines the relationship between individual VHCs, orbital forcing, and paleosol development. The Middle Passaic Formation of Late Triassic age is continuously exposed for over 30 meters along a railroad cut that follows Manatawny Creek near Pottstown, PA. Six VHCs were identified at this location and the upper most three were selected for detailed study due to their strong development. Three Van Houten Groups (VHGs), consisting of VHC Division 3, Division 1, and Division 2 respectively, were formed in order to group paleosol profiles (Division 3) with stratigraphically adjacent lacustrine units (Divisions 1 and 2) since the lakes directly affect the paleosurface through inundation and erosion. Petrographic analysis suggests that soils in this section only developed to the degree of Entisols or Protosols. Voids are lined with chalcedony and cored with calcite indicating diagenetic alteration. Molecular weathering ratio calculations proved unreliable due to diagenetic alteration of the strata. Magnetic susceptibility was measured on two intervals of the section, but is not well-suited to fractured, massive rock due to signal attenuation. Paleosol development is greater in instances where the overlying lake is poorly developed. Paleosols that are associated with a shallow lake or no lake likely have more time to develop than paleosols associated with deep lakes as the precipitation filling the lake would saturate the soil, hindering pedogenesis. The VHCs' ~21 kyr interval forces time to be the limiting factor for pedogenesis in this section, ending in either sedimentation or inundation. However, time is also tied to climate as it modulates from relatively moist to relatively drier within a VHC. Orbital forcing is the ultimate controlling factor in soil formation since time, climate, insolation, and precipitation are all interrelated and influenced by it. Relief is independent of orbital forcing and a possible control on soil formation within the Basin. Soils that formed distal from the bounding fault may not have been subject to inundation due to their higher elevation. Further research is needed to establish paleocatenary relationships of soil within the Newark Basin. / Geology

<p> Corn (Zea mays) is the dominant silage crop for irrigated dairy regions. Sorghum&rsquo;s (<i>Sorghum bicolor</i>) drought tolerance shows potential to be grown for silage under conditions of water shortages. A two year experiment was conducted in Five Points, CA to determine the yield and nutritive quality of forage corn (CORN), conventional sorghum (CONV) and brown midrib sorghum (BMR) at 100%, 80% and 60% of full irrigation (ETc) under a center-pivot irrigation system. Yields were measured and forage quality was determined using % Neutral Detergent Fiber (NDF), % NDF digested in 30 hours (NDFD30), % Crude Protein (CP), and % starch as quality parameters. Results in 2014 had a high degree of variability leading to no significances in yields. In 2015, CORN yield&rsquo;s reduced 57% more than BMR per unit of water, whilst CONV and BMR maintained yields from the 100 to 80% levels. The decline in NDFD30 with additional water was significantly larger in CONV than in CORN and in BMR. BMR had NDFD30 values up to 10% higher than those of CORN. CORN % starch decreased significantly with a 20% decrease in water application. Sorghum had a negligible amount of starch at all levels. CP decreased uniformly across all three types of forages with increased irrigation. We can conclude, therefore, that during water shortages, sorghum can provide high-yielding (>15 Mg/ha), digestible (>60% NDFD30) silage for use in dairy rations. However, sorghum must be supplemented with grain to compensate for the low starch.</p>

Silicon (Si) fertilization has gained attention in rice (Oryza sativa) production. However, the common soil-applied sources are amended at high rates, whereas the efficacy of foliar Si application is yet to be proven. A series of pot experiments were conducted to (1) elucidate the effects of different Si sources on grain yield and Si accumulation of rice supplied with varying P rates, and 2) evaluate Si absorption and uptake by rice via foliar- and soil-application of Si fertilizers. First, three phosphorus (P) rates (0, 112, and 224 kg P ha-1) and three Si sources: two soil-applied (wollastonite and silicate slag) and a liquid Si formulation applied as foliar spray at rates of 20, 40, and 80 mg Si L-1 were set as treatments. Silicon applied to soil (wollastonite and silicate slag) and leaves (Si solution) did not result in significant increase in rice P content and uptake in straw and grain. However, a corresponding increase in soil P content was observed with wollastonite application. Across all rice stages, wollastonite application consistently increased biomass Si content (P<0.05), but no significant increase in rice yield was observed with Si fertilization. For the second objective, two greenhouse experiments were conducted to determine if Si in solution can be absorbed through leaf surface and translocated within the plant. Three application rates of Si solution (20, 40, and 80 mg Si L-1) were sprayed to either whole rice plants or leaves of the primary third tiller of each plant, whereas for the second experiment, Si solution (80 mg Si L-1) was strictly applied to adaxial side of rice leaves, including two soil-sources and a check. The experiments were conducted in a randomized complete block design with at least four replications. There was no significant effect observed on rice growth and yield with Si fertilization. Foliar application of Si solution did not increase Si content of leaves, whereas wollastonite-treated rice attained the highest Si content (P<0.01). The outcomes of this series of greenhouse studies suggest that Si absorption on leaf surface did not take place as well as the translocation of Si within the plant.

Two line hybrid rice breeding is widely used in Asia and involves the use of environmentally-sensitive male sterile lines to achieve high grain yields compared to pure line varieties. Currently, there is limited information concerning the performance and inheritance of two indica male sterile lines 2008S and 2009S under U.S. field conditions. The first objective of the research herein was to characterize genetic male sterility of lines 2009S and 2008S under controlled environment conditions. Results showed that 2009S exhibited a thermosensitive response whereas little or no response was observed with changes in daylength. Furthermore, high pollen fertility was achieved at the proper developmental stage (flag leaf not fully exposed) under low temperature treatment for 10 days. On the other hand, 2008S showed partial fertility when subjected to short daylength and high temperature conditions. Both lines were completely male sterile at high temperature and long daylength under Louisiana field conditions. The second objective was two-fold: to investigate the inheritance of photoperiod, thermosensitive genetic male sterility (PTGMS) under field conditions and to evaluate SNP-based markers for male sterility. A three-year study of 2008S F2 and BC1F2 populations from 2012 to 2014 revealed a two-locus segregation model indicating two recessive genes acting on male sterility. Inheritance of 2009S in a two-year study from 2013 and 2014 displayed single locus segregation using F2 and BC1F2 populations demonstrating that male sterility was controlled by a single recessive gene. SNP markers at LOC_Os07g12130 and LOC_Os12g36030 in the 2008S background showed significant interactions with up to 65% variance explained in one population, while a SNP marker at LOC_Os02g12290 identified 90-100% of male sterile lines segregating in F2 and BC1F2 populations derived from 2009S. The third objective was to conduct QTL mapping for male sterility in populations derived from 2008S using a selective genotyping approach. A total of five major QTLs including those previously identified in LOC_Os07g12130 and LOC_Os12g36030 and eight new minor QTLs were detected using single marker analysis. Four QTL intervals were detected with a LOD score of greater than 3.0 using inclusive composite interval mapping (ICIM). QTLs identified will be useful in future studies to fine-map additional markers associated with male sterility and increase prediction accuracy for marker assisted selection. The fourth objective was to investigate the effect of the S5n wide compatibility gene on grain yield and spikelet fertility in hybrids derived from the SB5 RIL mapping population. Results from this study revealed that heterozygous S5n S5j hybrids produced significantly higher spikelet fertility and yield versus the hybrids carrying S5i S5j genotypes. Indel and SNP markers developed for the S5 locus successfully differentiated the three unique genotypes (S5n, S5i and S5j). Overall results from this study demonstrated that male sterile lines 2008S and 2009S were useful for two-line hybrid rice breeding under Louisiana conditions. New QTLs discovered and markers developed for male sterility and wide compatibility will help facilitate marker assisted breeding in developing male sterile lines for the LSU hybrid rice breeding program.

The practice of planting cover crops during fallow periods has increased due to the benefits provided to the soil system including improved nutrient cycling, addition of organic matter and a more diverse soil fauna resulting in better crop yield and an overall improvement of soil health. Research has shown that microbial activity is sensitive to changes in management practices and is a good indicator of whether the changes are benefiting the production system. To study the effects of cover type on corn (Zea mays L.) harvest parameters and soil chemical and biological properties a field trial consisting of a split plot design was established at LSU Agcenters Macon Ridge Research Station in northeast Louisiana. Treatments consisted of 8 covers: fallow, cereal rye (Secale cereal L.), forage radish (Raphanus sativus var. longipinnatus), berseem clover (Trifolium alexandrinum), crimson clover (Trifolium incarnatum L.), winter pea (Pisium sativum L.) and hairy vetch (Vicia villosa Roth) and 4 N rates (0, 235, 268 and 302 kg ha-1). Corn grain yield decreased by 20% after cover crop but responded to the addition of N both seasons. Cover crops had a positive effect on soil C:N over time, indicating active mineralization, and NO3- - N decreased almost three-fold between fall 2014 and spring 2015 (p<0.05). Cycling of C, N and S was also affected by cover crops; β-glucosidase and arylsulfatase activity were highest in spring 2015 (after cover crop termination) and averaged 73 and 32.9 mg p-nitrophenol kg-1 soil h-1, respectively. Microbial community structure shifted after cover crop with soil microbial communities under leguminous covers (hairy vetch, crimson clover, winter pea and berseem clover) separating from the brassica (forage radish) and grass (cereal rye) covers. Arbuscular Mycorrhiza Fungi (AMF) was higher (9.07 mol %) under the 0 N rate compared to the 263-302 kg ha 1 N rates (average 7.28 mol %) indicating the establishment of symbiotic relationship between plants and AMF as a response to nutrient deficient conditions. Cover crops established under Mid-South corn production systems show potential for improving the chemical and biological properties of soil.

<p> We use nonlinear least squares methods and Bayesian inference to calibrate soil properties using models for heat and groundwater transport in the shallow subsurface. We first assume a constant saturation in our domain and use the analytic solution to the heat equation as a model for heat transport. We compare our results to those using the finite element code, Adaptive Hydrology (ADH). We then use ADH to simulate heat and groundwater transport in an unsaturated domain. We use the Model-Independent Parameter Estimation (PEST) software to solve the least squares problem with ADH as our model. In using Bayesian inference, we employ the Delayed Rejection Adaptive Metropolis (DRAM) Markov chain Monte Carlo algorithm to sample from the posterior densities of parameters in both models. We find our results are consistent with those found using soil samples with empirical methods.</p>

End rot development in sweetpotato is caused by several pathogens and exacerbated by unfavorable environments. A critical need exists to know what factors in the environment trigger end rot development and how to manage the crop to minimize the incidence of end rots which are the overall objectives of this study. This research was divided into three studies: 1) Effect of environmental factors on expression of end rot in sweetpotato roots. Factorial combinations consisted of flooding/non-flooding; skinned/non-skinned; cured/non-cured; recommended storage/ambient storage are environmental variables not tested previously together in a systematic way. Results showed that curing at 29oC and 85-90% RH for five days and storage at 13oC and 85-90% RH were the critical factors mitigating end rot incidence. 2) Understand the role of calcium deficiency on end rot incidence. Relationship was observed between calcium and ethephon. Ethephon induced proximal and distal end rot incidences and decayed areas in sweetpotato. End rot symptoms are akin to blossom end rot in tomato caused by calcium deficiency. Increased rates of calcium in hydroponic solution increased calcium content in storage roots and reduced incidence of end rot. Calcium deficiency had impact on end rot incidence. 3) Identify expressed genes in storage roots treated with ethephon and 1-MCP. Molecular mechanisms triggered by the onset of end rot are unknown and may provide insight into plant protective mechanisms to exploit in a breeding program. This study identified differentially expressed genes (DEGs) using the annealing control primers (ACPs). DEGs identified are involved in protective mechanisms, transcriptional regulation, and an expressed protein (unknown). All 5 genes expressed in sweetpotato with end rot were confirmed by semi-quantitative reverse transcription polymerase chain reaction (sqRT-PCR) analysis. Genes differentially responded to 3.9 mM ethephon and 1 ppm 1-MCP. 1-MCP induced higher expression of TH2 and ATG8 than ethephon treated storage roots and minimized end rot incidence. This study furthered our knowledge of the role environment plays in inciting end rot development and how to minimize the incidence of end rots. Also, new genes were found that putatively lessen end rot and may have value as markers in breeding programs.

Sweet sorghum [Sorghum bicolor (L.) Moench] (SS) has been grown in the southern United States to produce syrup for many years. There is an interest in SS as a biofuel feedstock due to its high sugar content and high total biomass. Currently, little is known about the nutrient demand for SS or how it responds to tillage and fertilization. The objectives of this study were to: 1) evaluate the effects of tillage and phosphorus (P) and potassium (K) fertilization on SS agronomics, 2) evaluate nitrogen (N), P, and K uptake and nutrient partitioning in SS, 3) determine P and K maintenance fertilization rates for sugar and cellulosic ethanol production, and 4) evaluate the effects of tillage and maintenance fertilization on soil test extractable P and K at three depths after four years of a monocrop system. A split-plot, randomized complete block design with four replications was used to evaluate the effects of two tillage treatments (no-till system (NT) and conventional tillage (CT)) and two fertilization treatments (with maintenance (MF) and without maintenance (NMF)) on SS production from 2012 to 2015. The MF applied 45 and 67 kg ha-1 of P2O5 and K2O, respectively. The CT decreased days to 50% heading and increased the initial plant population. The NT increased the number of harvestable stalks which were derived from tillers. The MF increased plant height, stalk diameter, total biomass, and stalk biomass. The NT increased the P removal rate in green leaves. The MF application increased K concentration of stalk, green leaves, and the total K removal rate of the whole plant. The MF increased the P removal rate in the stalk. A 75 Mg ha-1 of SS would remove 40 and 145 kg ha-1 of P2O5 and K2O, respectively, when only the stalk is harvested. When the whole plant is removed, approximately 78 and 193 kg ha-1 of P2O5 and K2O would be removed, respectively. The MF application increased soil test exactable P at the 15 to 30 cm soil depth. Soil test extractable K was not affected by tillage and fertilization across the different soil depths.

While silicon (Si) fertilization is widely practiced in paddy rice production, the establishment of critical soil Si levels has remained understudied. This study was undertaken to: 1) determine the critical soil Si level for rice production in Louisiana using different extraction procedures, and 2) document the relationship between plant-available Si and select essential plant nutrients in soil and their uptake by rice. Field trials were established at 12 sites across Louisiana from 2013 to 2015. Si was applied as silicate slag (SiO3, 14% Si) at the rates of 0, 1, 2, 4, 6, and 8 Mg ha-1. Agricultural lime was also applied at (2 and 4 Mg ha-1) to evaluate the liming effect of slag in the main treatments. Treatments were arranged in a randomized complete block design with four replications. Soil samples collected at harvest were analyzed for pH, soil Si, heavy metals and plant-essential nutrients. Rice straw and panicle were analyzed for Si content; while panicle was analyzed for heavy metals and plant-essential nutrients. Analysis of variance and correlation analysis were performed for all measured variables using SAS 9.4. Slag application significantly increased the soil pH up to 1.4 units (p<0.05) in several sites. Rice grain yield was significantly (p<0. 1) increased in several sites by slag application, with the highest average grain yield obtained at application rates ranging between 1-4 Mg ha-1. The critical Si levels in soil ranged from 11.8 mg kg-1 (0.01 M CaCl2) to 771 mg kg-1 (0.1 M citric acid). The Si content in rice straw was negatively correlated with the panicle P (r = -0.25), S (r= -0.38), As (r = -0.33) and Cd (r = -0.39) but positively correlated with its Mn (r = 0.35) content. In general, soils with high initial Si and pH gave minimal responses to Si fertilization, while the Si content of soils with low initial Si was increased. Soil Si did not interfere with the uptake of most plant-essential nutrients, but the decrease in As and Cd contents of panicle shows that Si fertilization could be essential for improving grain quality of rice.

Ambrosia beetles have been a challenge to profitable nursery production for decades, with management recommendations focused on population monitoring and properly-timed insecticidal applications. Beetles disperse from forests starting in early spring, but few studies have determined the extent of this flight period, or how far they will fly into a nursery. And while the use of semiochemicals by ambrosia beetles has been widely examined, their use of visual cues including colors represents another gap in our knowledge. In addition to these under-studied behavioral traits, the available chemical control measures for ambrosia beetles are not completely effective, and repeated applications become costly for growers. Additional options are needed to reduce treatment frequency and to provide acceptable protection. The first experiment from 2012-13 determined beetle response to thirteen different trap colors. Mean beetle capture from opaque and red traps was significantly higher than from yellow or white traps, but we recommend that industry-standard black traps are adequate for ambrosia beetle monitoring. The second experiment from 2013-14 determined the timing of beetle flights and dispersal distance, as well as optimal trap and crop location. In addition to the well-documented spring flight, southeastern nursery managers need to be aware of a second, late-summer flight. Captures from traps placed at various distances (-25 to 200 m) from the forest/nursery interface showed a significant decreasing trend in numbers of beetles captured over increasing distance from the forest. Susceptible tree cultivars may gain added protection when placed deeper within nursery interiors and when baited traps line adjacent nursery edges. The third experiment from 2014-15 tested four treatments (kaolin clay, bifenthrin, kaolin + bifenthrin, and an untreated control) applied to ethanol-baited trees, with counts of new ambrosia beetle galleries compared roughly every other day for two weeks. While kaolin trees were better-protected than untreated trees at one day after treatment, subsequently there was no significant difference from untreated controls. And while there was a numerical reduction in attacks on kaolin + bifenthrin trees vs. bifenthrin trees, the effect was not statistically significant at any time.